Aug 2, 2014
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I realize this may be a stupid question for some people, but I'm having a hard time understanding it.

What I'm confused about is with Bl groups O & AB:
If O has no antigens but it has antibodies to A and to B, then it can't receive blood from anyone other than Bl group O because it'll agglutinate (since O has antibodies against the other blood groups). But how can it be a universal donor if it has antibodies against the other antigens?? I realize that it doesn't have antigens but how can it be given to the other blood groups when it possesses antibodies against both A & B?? Won't it agglutinate?

Same with Bl group AB - if it has no antibodies, but has antigens A & B, then how is it a universal recipient - when you give Bl group A to a person who has Bl group AB, then won't the anti-B antibodies in Bl group A cause agglutination (since AB has the B antigen)?

Also, another question is what type of antibodies are these? I was searching on SDN, and from what I understand, all the antibodies are IgM with the exception of bl group O which makes IgG antibodies to A & B which can cross the placenta. Yet Wikipedia says Bl group O "contains IgM antibodies against both A and B antigens." ??
 
Mar 26, 2013
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Medical Student
I realize this may be a stupid question for some people, but I'm having a hard time understanding it.

What I'm confused about is with Bl groups O & AB:
If O has no antigens but it has antibodies to A and to B, then it can't receive blood from anyone other than Bl group O because it'll agglutinate (since O has antibodies against the other blood groups). But how can it be a universal donor if it has antibodies against the other antigens?? I realize that it doesn't have antigens but how can it be given to the other blood groups when it possesses antibodies against both A & B?? Won't it agglutinate?

Same with Bl group AB - if it has no antibodies, but has antigens A & B, then how is it a universal recipient - when you give Bl group A to a person who has Bl group AB, then won't the anti-B antibodies in Bl group A cause agglutination (since AB has the B antigen)?

Also, another question is what type of antibodies are these? I was searching on SDN, and from what I understand, all the antibodies are IgM with the exception of bl group O which makes IgG antibodies to A & B which can cross the placenta. Yet Wikipedia says Bl group O "contains IgM antibodies against both A and B antigens." ??
My understanding is that donated blood is split in to red blood cells and plasma (or is it serum?). Type O- people are universal donors of CELLS (no antigens to be attacked), Type AB+ people are universal donors for plasma (no antibodies to cause issues).

I don't think your other questions are terribly step 1 relevant, they just seem to care about Rh isoimmunization. I also don't understand the issue well enough myself to add much clarity.
 
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Jul 28, 2015
66
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Medical Student
Type O blood donate blood cells and not plasma since their RBC don't have antigen. While AB blood can donate plasma since they don't have antibodies against any RBC antigen.


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EmetyreUSMLEStep1Tutor1

2+ Year Member
Jul 11, 2015
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I realize this may be a stupid question for some people, but I'm having a hard time understanding it.

What I'm confused about is with Bl groups O & AB:
If O has no antigens but it has antibodies to A and to B, then it can't receive blood from anyone other than Bl group O because it'll agglutinate (since O has antibodies against the other blood groups). But how can it be a universal donor if it has antibodies against the other antigens?? I realize that it doesn't have antigens but how can it be given to the other blood groups when it possesses antibodies against both A & B?? Won't it agglutinate?

Same with Bl group AB - if it has no antibodies, but has antigens A & B, then how is it a universal recipient - when you give Bl group A to a person who has Bl group AB, then won't the anti-B antibodies in Bl group A cause agglutination (since AB has the B antigen)?

Also, another question is what type of antibodies are these? I was searching on SDN, and from what I understand, all the antibodies are IgM with the exception of bl group O which makes IgG antibodies to A & B which can cross the placenta. Yet Wikipedia says Bl group O "contains IgM antibodies against both A and B antigens." ??
Universal donor of RBC!!!111 not plasma. AB is universal donor of PLASMA(not RBC)
 
Aug 2, 2014
151
54
Everything above that the posters responded was correct; I just wanted to add: that according to Goljan: to test for cross-match, you mix the patient's serum with the donor's RBC's to see if they're compatible.
 
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